1. Field of the Invention
The present invention relates to a new ultraviolet radiation projector and a new optical image forming apparatus. More specifically, the present invention relates to an ultraviolet radiation projector serving as a light source for exposing an ultraviolet sensitive material and an optical image forming apparatus for forming a desired two- or three-dimensional image by using the ultraviolet radiation projector.
2. Description of the Prior Art
An optical image forming method is one of the conventional methods of forming desired images. For example, a liquid or sheet-like synthetic resin (to be referred to as a photosensitive resin hereinafter) cured or decomposed upon radiation of an ultraviolet beam is positively or negatively exposed with an ultraviolet beam having a predetermined wavelength to form a desired image on the photosensitive resin.
A conventional apparatus includes a light source such as ultraviolet emission type CRT for image forming. A focusing optical member is inserted between a panel surface of the CRT and a surface of the photosensitive resin, whereby an ultraviolet beam from the emission surface of the CRT is focused onto the surface of the photosensitive resin through the focusing optical member to expose the photosensitive resin.
An example of the above apparatus is described in Japanese Patent Laid-Open No. 288844/1987.
The optical image forming apparatus described in the prior art mentioned above has the following problems. In this conventional optical image forming apparatus, a light guide is arranged on the emission surface of the CRT to collimate the ultraviolet beam, and a photosensitive resin is supplied to an output end face of the light guide, so that flatness of the output end face of the light guide directly determines precision of an image to be formed. For this reason, very high working precision of the output end face is required. For example, when the photosensitive resin cured remains attached to the output end face, the image pattern formed is not only damaged, an image to be formed upon supply of a new photosensitive resin material is but also damaged, furthermore the cured resin left on the output end face adversely affects the ultraviolet beam optically. In addition, a temperature difference inevitably occurs between the photosensitive resin and the panel surface of the CRT due to their contact. An application for the CRT is limited by the temperature difference.